v3.26.1
Receivables from Policyholders - Allowance for Expected Credit Losses (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Premium Receivable, Allowance for Credit Loss [Roll Forward]          
Balance, Beginning of Year $ 1.5 $ 2.4 $ 2.0 $ 2.9  
Provision for Expected Credit Losses 9.2 13.2 18.8 26.9  
Write-offs of Uncollectible Receivables from Policyholders (9.5) (13.6) (19.6) (27.8)  
Balance, End of Period 1.2 2.0 1.2 2.0  
Premiums Receivable, Net 972.5 1,050.3 972.5 1,050.3  
Variable Interest Entity, Primary Beneficiary          
Premium Receivable, Allowance for Credit Loss [Roll Forward]          
Premiums Receivable, Net 6.2 11.6 6.2 11.6 $ 10.4
Operating Segments          
Premium Receivable, Allowance for Credit Loss [Roll Forward]          
Balance, Beginning of Year 1.4 2.2 1.9 2.6  
Provision for Expected Credit Losses 9.2 13.2 18.8 26.7  
Write-offs of Uncollectible Receivables from Policyholders (9.5) (13.6) (19.6) (27.5)  
Balance, End of Period 1.1 1.8 1.1 1.8  
Premiums Receivable, Net 967.6 1,042.9 967.6 1,042.9  
Non-Core Operations          
Premium Receivable, Allowance for Credit Loss [Roll Forward]          
Balance, Beginning of Year 0.1 0.2 0.1 0.3  
Provision for Expected Credit Losses 0.0 0.0 0.0 0.2  
Write-offs of Uncollectible Receivables from Policyholders 0.0 0.0 0.0 (0.3)  
Balance, End of Period 0.1 0.2 0.1 0.2  
Premiums Receivable, Net 4.9 7.4 4.9 7.4  
Specialty Property & Casualty Insurance | Operating Segments          
Premium Receivable, Allowance for Credit Loss [Roll Forward]          
Balance, Beginning of Year 1.4 2.2 1.9 2.6  
Provision for Expected Credit Losses 9.2 13.2 18.8 26.6  
Write-offs of Uncollectible Receivables from Policyholders (9.5) (13.6) (19.6) (27.4)  
Balance, End of Period 1.1 1.8 1.1 1.8  
Premiums Receivable, Net 956.7 1,031.8 956.7 1,031.8  
Life Insurance | Operating Segments          
Premium Receivable, Allowance for Credit Loss [Roll Forward]          
Balance, Beginning of Year 0.0 0.0 0.0 0.0  
Provision for Expected Credit Losses 0.0 0.0 0.0 0.1  
Write-offs of Uncollectible Receivables from Policyholders 0.0 0.0 0.0 (0.1)  
Balance, End of Period 0.0 0.0 0.0 0.0  
Premiums Receivable, Net $ 10.9 $ 11.1 $ 10.9 $ 11.1